Just like I was saying before......
They had to bail on the Z28 package, but didnt want to hurt sales..........
So rather than let the public decide "oh Im just gonna wait another year and get the Z28" they had to completey call it dead so that people will buy an SS and then upgrade to the Z28 later.
I also think that they wanted Transformers 2 to be a big help on it..... but since that flopped, waiting till Transformers 3 will certainly be a better decision from the business side of the house.
Plus that gives them like 3 years to get some super efficient econo-boxes on the roads to offset the fleet average fuel mileage. Making it OK to have the Z28... and 3 years to redesign the motor to make 550-600HP at 24MPG